Device for counterbalancing window sashes



5, 1967 L. L. ANDERSON 3,335,455

DEVICE FOR COUNTERBALANCING WINDOW SASHES Filed Jan. 25, 1965 I "IIIIIII/ L. Sogd L. CAHdQI JO L United States Patent 3,335,455 DEVICE FOR COUNTERBALANCING WINDOW SASHES Lloyd L. Anderson, Rockford, Ill., assignor, by mesne assignments, to Amerock Corporation, Rockford, Ill., a

corporation of Connecticut Filed Jan. 25, 1965, Ser. No. 427,702 Claims. (Cl. 16198) This invention relates to a device for counterbalancing window sashes which slide vertically in a frame, and more particularly, to a counterbalancer of the type including a drum journaled On an axle in a case which is mounted adjacent the top of the frame with a cord wound around the drum and connected to the side of the sash. In such devices, a torsion spring wrapped around the axle acts between the axle and the drum to urge the latter in a direction to apply tension to the cord and thereby exert an upward force on the sash sufficient to offset the weight of the sash.

The primary object of this invention is to provide a novel means of attaching and supporting the spring between the axle and drum to prolong the life and effectiveness of the spring.

Other objects and advantages of the invention will become apparent from the following detailed description taken in connection with the accompanying drawing, in which FIGURE 1 is a fragmentary perspective view of a window including a counterbalancer of the type which embodies the novel features of the present invention,

FIG. 2 is an enlarged fragmentary sectional view taken along the line 22 of FIG. 1,

FIG. 3 is an enlarged fragmentary sectional View taken along the line 3-3 of FIG. 2,

FIG. 4 is an enlarged fragmentary sectional view similar to FIG. 3, taken of a prior device not embodying the subject invention,

FIG. 5 is an enlarged fragmentary view of that portion of the spring immediately adjacent the axle,

FIG. 6 is an enlarged fragmentary view of the drum showing the spring and anchor for fastening the spring to the drum.

As shown in the drawings for purposes of illustration, the invention is embodied in a device 10 for counterbalancing two window sashes 11 and 12 mounted in a conventional frame 14 to slide vertically therein. The upper sash 11 is slidable downwardly in the frame to open the window at the top and the lower sash 12 is slidable upwardly to open the window at the bottom. To counterbalance the sashes, the device 10 exerts an upward force on the sashes through the cords 15 and 16 sufficient, in cooperation with the friction between the sashes and the frame, to offset the weight of the sashes and sustain the latter in selected positions in the frame.

In the present instance, the counterbalancer includes a flat, box-like case 18 mounted adjacent the top of the frame, preferably recessed and held in place by screws (not shown) driven into the frame. The case is of sheet metal construction and includes a bottom wall 19 (see FIG. 2) and a top wall 20 with one of these walls having flanges bent over to form the side walls. Journaled in the case on a tubular axle 21 is a drum 22 comprising a hollow cylinder 24 including a lower end wall 25 and an open upper end. Where, as here, two sashes are mounted in one frame, two such axles and drums are disposed in the case, one for each sash, but only one is shown and described in detail with the understanding that the other is identical.

To rotatably support the drum 22 in the case, a bearing 28, which preferably is molded of some suitable anti- 3,335,455 Patented Aug. 15, 1967 friction plastic, is supported on the bottom wall 19 of the case. This bearing 28 is held in place by some suitable means such as screws (not shown) extending through the bottom wall 19 and includes an annular recess 26 on which the lower end of the drum rests. A center opening 30 of the drum telescopes over an upstanding cylindrical flange or hub 29 of the bearing to hold the drum concentric about the axle.

The axle 21 spans the bottom wall 19 and the top wall 20 and is formed to telescope snugly into a center opening 29a in the hub 29. Arcuate tabs 31 and 32 on the upper and lower ends of the axle project through the top and bottom walls 19, 20 respectively, to hold the axle against turning. Thus the drum may rotate about the axle on the hub 29 which constitutes an anti-friction bearing.

As shown in FIGS. 1-3, the cord 15 is wound about the drum and fastened thereto by a knot 36 extending through a slot 38. The free end of the cord extends horizontally off the drum and passes along a groove 39 of a guide 40, and downwardly through a hole 41 in the bottom wall 19 adjacent one end of the case. The cord thereafter extends to the sash 11 and is fastened to the side thereof. The guide 40 is preferably made of sheet metal and is supported adjacent the bottom wall and between the side walls, and is held there by some suitable means such as tabs (not shown) formed integrally with the guide and extending through alined openings in these walls.

To control the winding of the cord 15 onto the drum, the outer periphery of the drum is formed with a helical groove 42 which guides the cord evenly onto the drum. With the foregoing arrangement, turning the drum in a direction to wind the cord places the cord under tension to urge the sash upwardly. To urge the drum in this direction, an elongated flat spring 44 is wrapped spirally around the upper portion of the axle 21 with the inner end fastened to the axle and the outer end fastened to the drum. The spring is wrapped about the axle so that unwinding the cord as the sash is lowered winds the spring.

The spring 44- is attached between the drum and axle in a novel manner to hold it concentric about the axle and thus limit sidewise flexing which can lead to breakage of the spring. For a better understanding of such flexing, FIG. 4 illustrates one way in which the spring has been supported in prior art devices. In this illustration, a drum 22' is journaled about an axle 21' with a spring 44' having an end A attached to the drum and end B attached to the axle. The spring is partially wound as is normal in counterbalancing devices, and is therefore urging the drum to turn in the counterclockwise direction to wind the cord 15'. The force exerted on the drum by the weight of the sash pulling on the cord 15 is urging the drum to rotate clockwise as indicated by the arrow C. In prior spring devices such as the one illustrated here, the spring in offsetting this force C on the drum to counterbalance the sash is shifted sidewise as illustrated. The direction of shifting of the spring with respect to the axle changes as the drum revolves causing each portion of the spring to flex towards and away from the axle, once per revolution of the drum. This flexing action shortens the useful life of the spring and causes binding of the spring as it winds and unwinds, thus resulting in an uneven or jerking force being exerted on the drum and cord as the sash is raised and lowered.

In accordance with the present invention, the spring 44 is mounted in a novel manner so that it may be anchored securely to the axle 21 and, at the same time, the lateral flexing of the spring is reduced thereby minimizing the possibility of the spring failing, especially adjacent the inner turns 51, 52 which connect the spring to the axle. Thus, these turns may be annealed or otherwise treated to be nonresilient and permit a firm connection between the spring and the axle with little chance of the spring breaking at the point where annealing begins since this sidewise flexing of the spring is materially reduced.

To reduce lateral fiexing of the spring 44, the outer end portion 53 of the spring is held generally concentric with the wall 24- of the drum 22. From this end portion the spring gradually merges into the spiral form. With this arrangement the spring is substantially centered about the axle 21 and remains so as it is wound and unwound. As a result lateral flexing is, for all practical purposes, eliminated and the spring is subjected only to the flexing which results from the winding and unwinding.

In the present instance, the means for holding the outer end portion 53 of the spring 44 concentric with the drum wall 24 comprises an anchor 46 rigidly supported from the end wall 25 of the drum. This anchor extends normal to the end wall and includes a radially outward facing wall 48 extending generally concentric with the drum Wall 24. The outer end 53 of the spring 44 is positioned in abutting relationship to the wall 48 and fastened to the anchor 46 by having the end 53a partially bent back on itself in a radially inward direction, with this bent end hooked around the anchor. The spring is thus held in its normal spiral configuration while urging the drum to rotate after being wound. Any force tending to cause sidewise movement of the spring as explained before, is opposed by the wall 48 abutting the spring to thus maintain the spring concentric about the axle. Contact between adjacent turns and flexing of the spring is thus limited Since such sidewise flexing of the spring is substantially eliminated, it is possible to fasten the spring tightly to the axle without reducing the life of the spring. For this purpose, the inner end 49 is bent normal to the spring to fit into a slot 50 in the axle alined to receive the spring end. To hold the end 49 in the slot 50 as the spring is wound and unwound, the adjacent turn 51 is fitted closely adjacent to the axle to hold the end 49 in the axle slot. Also, adjacent turns 52 may also be so formed for the same purpose. To permit these turns to remain closely adjacent to the axle, since the spring is wound and unwound there is a tendency for the spring to spiral away from the axle, the inner end of the spring is annealed or otherwise treated to lessen the resiliency of the turns 51, 52. Thus, the spring is made fast by the inner end fitting into the axle slot and firmly held in place by the adjacent abutting turns which are closely wound about the axle.

The spring 44 is thus supported between the drum 22 and the axle 21 in a manner to be wound when the cord 15 is unwound from the drum periphery to urge the drum to rotate and thereafter wind the cord for counterbalancing the attached sash. During such rotation of the drum, the spring is maintained in a spiral configuration concentric about the axle and sidewise flexing of the spring is held to a minimum. Therefore, the spring winds and unwinds in a smooth and even manner for an effective and smooth operation of the counterbalancing device, with the useful life of the spring shown to be greatly extended.

I claim as my invention:

1. A device for counterbalancing a Window sash slidable up and down in a frame, said device including, in combination, a support mountable adjacent the top of the frame, an axle fixed to said support, a drum journaled on said support to rotate about said axle and having a cylindrical wall, a flexible element having one end anchored to said drum and wrapped around the outer surface of said wall, the other end of said element adapted for connection to the window sash, an elongated spring spirally wrapped in a plurality of turns around said axle with the inner end of the spring fixed to said axle and the outer end fixed on said drum whereby turning of the drum in one direction winds the spring which thereafter urges the drum to rotate in the opposite direction, the inner end portion of said spring being nonresilient and wrapped for at least one complete turn closely around said axle, and means rigid with said drum and concentric with the wall of the drum and about which the outer end of the spring is wrapped inwardly toward the center of the drum, said means being operable to hold the outer end portion of said spring concentric with said drum wall thereby maintaining said spring concentric about said axle.

2. A device for counterbalancing a window sash slidable up and down in a frame, said device including, in combination, a support mountable adjacent the top of the frame, an axle fixed to said support, a drum journaled on said support-to rotate about said axle and having a a cylindrical wall, a flexible element having one end anchored to said drum and wrapped around the outer surface of said wall, the other end of said element adapted for connecting to the window sash, an elongated spring spirally wrapped in a plurality of turns around said axle, the spring inner end being bent inwardly, said axle including an opening alined to receive said bent end to prevent the spring from turning about said axle, the outer end of said spring fixed to said drum whereby turning of the drum in one direction winds the spring which thereafter urges the drum to rotate in the opposite direction, the inner end portion of said spring being nonresilient and wrapped for at least one complete turn closely around said axle to hold said bent end in said axle opening, and means rigid with said drum and concentric with respect to the wall thereof and about which the outer end of the spring is wrapped inwardly toward the center of the drum, said means being operable to hold the outer end portion of said spring concentric with said drum wall thereby maintaining said spring concentric about said axle.

3, A device for counterbalancing a window sash slidable up and down in a frame, said device including, in combination, a support mountable adjacent the top of the frame, an axle fixed to said support, a drum journaled on said support to rotate about said axle and having a cylindrical wall, a flexible element having one end anchored to said drum and wrapped around the outer surface of said wall, the other end of said element adapted for connecting to the window sash, an elongated spring spirally wrapped in a plurality of turns around said axle, the spring inner end being bent inwardly, said axle including an opening alined to receive said bent inner end to hold said spring from turning about said axle, an elongated anchor rigidly supported interiorly of and by said drum and having a radially outward facing wall extending concentric to said drum wall, the inner end portion of said spring being nonresilient and wrapped for at least one turn closely around said axle to hold said bent inner end in said axle opening, the outer end portion of the spring being in contact with said anchor wall and having an end portion looped inwardly toward the center of the drum to hold the outer end portion of said spring concentric with said drum wall thereby maintaining said spring concentric about said axle, said spring acting, when said drum is rotated in one direction, to bias the drum for rotation in the opposite direction.

4. A device for counterbalancing a window sash slidable up and down in a frame, said device including, in combination, a support mountable adjacent the top of the frame, an axle fixed to said support, a drum journaled on said support to rotate about said axle and having a cylindrical wall, a flexible element having one end anchored to said drum and wrapped around the outside of said wall, the other end of said element adapted for connecting to the window sash, an elongated spring spirally wrapped in a plurality of turns around said axle, with spring inner end being bent radially inwardly, said axle including an opening to receive said bent end and hold said spring from rotating about said axle, an elongated, arcuate anchor supported from said drum adjacent the outer end of said spring and having a radially outward facing wall extending concentric with but spaced from said drum wall, said spring outer end being fixed to said drum by passage along said outward facing anchored wall and thereafter being bent around the end of said anchor inwardly toward the center of said drum, the inner end portion of said spring being nonresilient and wrapped for at least one turn closely around said axle to hold said bent end in said axle opening whereby turning of the drum in one direction winds the spring which thereafter urges the drum to rotate in the opposite direction and the anchor wall holds the spring concentric about said axle to prevent sidewise flexing of the spring.

5. A device for counterbalancing a window sash slidable up and down in a frame, said device including, in combination, a support mountable adjacent the top of the frame, an axle fixed to said support, a drum journaled on said support to rotate about said axle and having a cylindrical wall, a flexible element having one end anchored to said drum and wrapped around said Wall, the other end of said element adapted for connecting to the window sash, an elongated spring spirally wrapped in a plurality of turns around said axle, with spring inner end being bent radially inwardly, said axle including an opening to receive said bent end and hold said spring from rotating about said axle, an anchor supported from said drum adjacent the outer end of said spring and having a radially outward facing wall extending concentric to said drum wall, said spring outer end being fixed to said drum by extending along said outward facing anchor wall and thereafter being bent around said anchor, the inner end portion of said spring being annealed to be non-resilient over a plurality of convolutions wrapped closely around said axle to hold said bent end in said axle opening where by turning of the drum in one direction Winds the spring which thereafter urges the drum to rotate in the opposite direction and the anchor wall holds the spring concentric about said axle to prevent sidewise flexing of the spring.

References Cited UNITED STATES PATENTS 1,503,470 8/1924 Biro et a1. 16-198 2,192,101 2/1940 Peskin 267-1 3,146,488 9/1964 Dahlstrom 16-198 FOREIGN PATENTS 472,238 2/ 1929 Germany.

3,535 8/ 1919" Netherlands.

MARVIN A. CHAMPION, Primary Examiner. EDWARD C. ALLEN, Examiner.

J. H. MCGLYNN, Assistant Examiner. 

1. A DEVICE FOR COUNTERBALANCING A WINDOW SASH SLIDABLE UP AND DOWN IN A FRAME, SAID DEVICE INCLUDING, IN COMBINATION, A SUPPORT MOUNTABLE ADJACENT THE TOP OF THE FRAME, AN AXLE FIXED TO SAID SUPPORT, A DRUM JOURNALED ON SAID SUPPORT TO ROTATE ABOUT SAID AXLE AND HAVING A CYLINDRICAL WALL, A FLEXIBLE ELEMENT HAVING ONE END ANCHORED TO SAID DRUM AND WRAPPED AROUND THE OUTER SURFACE OF SAID WALL, THE OTHER END OF SAID ELEMENT ADAPTED FOR CONNECTION TO THE WINDOW SASH, AN ELONGATED SPRING SPIRALLY WRAPPED IN A PLURALITY OF TURNS AROUND SAID AXLE WITH THE INNER END OF THE SPRING FIXED TO SAID AXLE AND THE OUTER END FIXED ON SAID DRUM WHEREBY TURNING OF THE DRUM IN ONE DIRECTION WINDS THE SPRING WHICH THEREAFTER URGES THE DRUM TO ROTATE IN THE OPPOSITE DIRECTION, THE INNER END PORTION OF SAID SPRING BEING NONRESILIENT AND WRAPPED FOR AT LEAST ONE COMPLETE TURN CLOSELY AROUND SAID AXLE, AND MEANS RIGID WITH SAID DRUM AND CONCENTRIC WITH THE WALL OF THE DRUM AND ABOUT WHICH THE OUTER END OF THE SPRING IS WRAPPED INWARDLY TOWARD THE CENTER OF THE DRUM, SAID MEANS BEING OPERABLE TO HOLD THE OUTER OF THE DRUM, SAID SAID SPRING CONCENTRIC WITH SAID DRUM WALL THEREBY MAINTAINING SAID SPRING CONCENTRIC ABOUT SAID AXLE. 